1. Field of the Invention
This invention relates to a friction reducing stabilizer bar for an automotive vehicle.
2. Description of Related Art
Torsional stabilizer bars have proven useful in vehicles for many years. Such stabilizer bars commonly employ a transverse torsion bar segment pivotally attached to the vehicle chassis and leading or trailing longitudinal segments attached to a control arm, wheel carrier or telescoping strut. Examples of stabilizer bars having this particular configuration are shown in U.S. Pat. Nos. 2,660,449; 3,181,885; 3,733,087; 4,066,278; 4,143,887. Ford Motor Company Shop Manual for 1986 model Taurus and Sable automobiles at pages 14-32-1 and 14-32-6 shows a further example of the conventional stabilizer bar in which each free end of the stabilizer bar is attached to the inboard side of a MacPherson strut by means of a link equipped with a rubber bushing at either end.
Each of the previously mentioned stabilizer bar systems acts in a manner such that when the vehicle body tries to roll in relation to the suspension system during a turning maneuver, the added load caused by centrifugal force acting upon the wheel at the outside of the corner is partially transferred to the wheel at the inside of the corner, with the result that excessive body roll is prevented.
Designers have sought to enhance the function of stabilizer bars in several ways. U.S. Pat. No. 4,648,620, which is assigned to the assignee of the present invention, discloses an adjustable stabilizer bar in which the torque reactive capacity of the primary torsional reaction segment is adjustable. U.S. Pat. No. 4,153,272 discloses a stabilizer bar assembly in which the lever arms of the stabilizer bar are pivotally connected to the steering knuckles by means of links such that the lever arm at the inside of the turn is moved downwardly by a steering-related force transmitted by way of the respective connecting link, whereas the lever arm at the outside of the turn is moved upwardly. Finally, U.S. Pat. No. 4,632,423 discloses a stabilizer bar system in which the crank ends of the stabilizer bar attach to a telescoping suspension strut by means of a link equipped with a ball joint at either end.
One of the drawbacks inherent with MacPherson strut and other types of telescoping strut suspensions is that friction developed within the strut due to the bending moment resulting from wheel loading may cause undesirable ride characteristics. This undesirable characteristic stems from the fact that friction within the strut necessitates that a fairly high level of force be input to the strut merely to begin telescoping the strut in the jounce or rebound direction. Accordingly, it is desirable to reduce friction within the strut, by reducing the bending load that adds to strut friction.
One commonly employed means for reducing the undesirable bending load within a telescoping strut is shown in previously mentioned U.S. Pat. No. 4,632,423, in which the lower spring seat of a MacPherson strut is offset to the outboard side of the vehicle. This arrangement is somewhat disadvantageous because the offset position of the suspension spring increases the package dimensions of the final suspension, at the expense of interior spaciousness of the automobile. U.S. Pat. No. 4,615,537, which is assigned to the assignee of the present invention, discloses yet another means for altering friction of a telescoping strut. As set forth in the '537 patent, the operating friction of a strut may be reduced by rotating either or both ends of the strut outward with respect to the balance of the strut. This system produces only a fixed reduction in strut friction because the magnitude of the force tending to reduce the friction is fixed at the time the strut is rotated outward by the wedge or other device shown in the '537 patent.
The present invention offers a means for reducing friction within telescoping struts not only statically, that is when the struts are not moving in the telescoping jounce and rebound directions, but also in a dynamic fashion.
It is an advantage of the present invention that a stabilizer bar according to this invention will reduce friction within the telescoping struts of a suspension.
It is yet another advantage of the present invention that a stabilizer bar according to this invention may be utilized without the need for additional attaching links.
It is yet another advantage of the present invention that a stabilizer bar according to this invention will reduce vehicular noise resulting from road imperfections.
It is yet another advantage of the present invention that a stabilizer bar according to this invention will have an operating characteristic such that as the wheels of the vehicle go into the jounce position the stabilizer bar will exert force against the telescoping struts of the suspension in a direction tending to minimize friction within the telescoping struts. This force will automatically decrease as the vehicle moves in the direction of the normal ride height.